The present invention relates to a valve for installation in high-pressure gas piping systems, for example, in fuel cell systems, in which a valve disc and a valve seat are brought into close contact via a sealing member composed of an elastic material and provided on one of them.
Valves in which a sealing member composed of an elastic material such as rubber is disposed on either a valve disc or a valve seat is known as the conventional valve designed for high-pressure fluids (for example, see Japanese Patent Laid-open Publication No. 2003-240149 (Page 4 and FIG. 2) and Japanese Utility Model Laid-open Publication No. H5-73368 (Page 9 and FIG. 2). Among such valves, in pilot electromagnetic valves described in Japanese Patent Laid-open Publication No. 2003-240149, in which the sealing member is disposed on the valve seat, the sealing member and valve disc are so formed that the sealing member pressed by the high-pressure fluid when the valve disc is open will not be damaged by the deformation in the flow direction of the fluid.
However, in such conventional valves, if a state is assumed with a large difference in pressure between the primary side and the secondary side, when the valve is opened, the fluid rapidly flows to the secondary side and a large force is rapidly applied by the fluid to the sealing member. The resultant problem is that the sealing member, which is an elastic substance, easily undergoes large deformation that easily leads to loss of durability.
Increasing hardness of the sealing member is apparently the simplest way to resolve the above-described problem. However, if a state is assumed in which the difference in pressure between the primary side and secondary side is small, the force applied to the sealing member when the valve is closed is insufficient and this time the sealing capability is easily lost.